SAN FRANCISCO – People use many adjectives to describe Barry Bonds – amazing, unbelievable, difficult, focused. But none encapsulates the man some consider the best baseball player ever better than selective.

It is selectivity that has made him one of the most prolific hitters of all time. The Giants’ left fielder rarely swings at a bad pitch, and has mounted an assault on the record books in the past four years.

But it is Bonds’ selectivity away from the field that has made him the most difficult sports superstar to love. A private man by nature, Bonds lets few people get a glimpse of who he really is. That, combined with an open disdain for the media, has led many to label him as surly and a malcontent.

“He thinks everybody don’t like him,” said Willie Mays, Bonds’ godfather. “Go talk to him and I guarantee you’ll see a different side of him. With my guy, sometimes you have to read between the lines.”

Between the lines is where Bonds is at his best. It is there that he does not have to hear the whispers about steroids, does not have to answer questions and can just be a baseball player.

But Bonds’ legacy may have as much to do with his talent as it does with public opinion, making Bonds’ place in history complex.

While his skill on a baseball field is undeniable, the public at large has never embraced him. The ongoing BALCO steroids probe has further tainted his reputation with many people treating Bonds as if he is guilty until proven innocent. All of this raises the question: How will Bonds’ career be punctuated – with an exclamation point or an asterisk?

IN the current sports world, there is no parallel to a Bonds at-bat. The buzz in the stadium is palpable. People stop talking, delay the bathroom break and 40,000 pairs of eyes focus on No. 25. When he comes to Shea Stadium on Tuesday to begin a three-game series with the Mets, the city’s attention will shift to Queens.

Throughout sports history there have been circumstances that make you hold your breath in anticipation – Jim Brown taking a handoff, Gretzky with the puck behind the net and Jordan with the ball as time winds down. Bonds with a bat in his hand is the current standard-bearer.

The problem is getting the pitcher to throw him strikes. No one has walked as much as Bonds since Moses was guiding folks through the desert. Through Friday, he had 39 walks, 18 intentional (more than any other team in baseball).

“I don’t know any other baseball players that have gone through what I’ve gone through,” Bonds said in an exclusive interview with The Post at his locker at SBC Park.

The amazing part is when Bonds does get a pitch to hit, he usually deposits it over the fence. Of his 25 hits this season, 10 are home runs. He had a seven-game consecutive home run streak last month, and surpassed Mays for third place on the all-time list with 668, trailing just Hank Aaron and Babe Ruth.

“He had more home runs than outs during eight games – five outs, seven home runs,” said John Thorn, editor of Total Baseball. “We’re not going to see that happen again. That’s Little League territory.”

Eye-popping statistics are nothing new for Bonds. In the last four years he has rewritten baseball’s record books, passing names like Ruth, Williams and Musial along the way. He holds the single-season marks in home runs, walks, slugging percentage, on-base percentage and on-base plus slugging. He also is one of four players to have hit 300 home runs and stolen 300 bases but Bonds is the only person to have more than 500 in both.

At 39 years of age, Bonds has shown no signs of slowing He is batting .472 and has reached base 69.6 percent of the time. His 10 homers are as many as the entire Expos lineup. Batting in the middle of a dismal Giants lineup, Bonds is as vulnerable as a rowboat in a hurricane. While in past years he had Jeff Kent or Matt Williams batting behind him, this year he has been left with Pedro Feliz or Jeffrey Hammonds protecting him.

This has led to pitchers taking the bat out of his hands with intentional walks. Even when they do pitch to him, they very carefully dance around the corners, rarely throwing him a strike. Bonds has struck out only six times this year.

“I don’t think there’s anybody in history who has done what he has done,” Hall of Famer Reggie Jackson told The Post’s George King. “You can’t have 15 at-bats a week and 15 base on balls. I don’t know anyone in the history of baseball who has been able to save his swings. He is affected by nothing. He is either a robot or one strong human being.”

The walks have left the offense-deprived Giants frustrated and the fans who paid to see Bonds swing booing.

“You’re always surprised now when they throw him a strike,” said Jules Tygiel, a professor at San Francisco State and baseball historian who attends about 20-30 Giants games a year. “The way they’re walking him, everybody’s going to get deprived of the best show in baseball.”

Bonds, for his part, has not openly shown disgust at the way pitchers have avoided him. As he walked through the dugout on his way to take batting practice last week, someone suggested it might be the only time he gets to take a swing all night. Bonds just looked straight ahead and said, “I don’t give a [bleep].”

As difficult as Bonds is for pitchers to figure out, he’s even tougher to understand away from the field. It is hard to gauge how much he cares about his image. He likes to tell reporters he does not care about what is said or written about him. Yet he has two personal publicists, a marketing director and a creative director.

This year, he became the first player to drop out of the players union’s group-licensing agreement, meaning baseball could not use his name or likeness in products like baseball cards or video games.

“He does care,” his publicist, Rachael Vizcarra, said. “Barry’s just a very private person.”

Both current and ex-teammates swear Bonds is not what he is portrayed to be. They say he jokes and interacts with other players and treats them well; it’s just the media doesn’t see that.

Bonds grew leery of reporters at an early age while watching his father Bobby and godfather Mays play. His father was criticized for not living up to expectations, and rumors of heavy drinking circulated. The seeds of that distrust grew into Bonds’ current view of the media.

“I was born in this game,” Bonds said. “There’s a difference. I’ve seen the positive side and I’ve seen a lot of negative things. I happened to have a father in the game. I’ve seen how baseball treated one person and how they treated that person at a different time. I wasn’t going to go through that.”

At SBC Park, Bonds presence is felt everywhere. Banners hang around the stadium with his picture; his name appears in left, center and right fields. In the Giants’ clubhouse, Bonds occupies one small wall. He has three lockers, and only assistant strength and conditioning coach Greg Oliver is in the same row. In front of his lockers is a large, black recliner that sits in front of his personal television. He seems isolated from everyone else in the room. With teammates sitting on the team couches in the middle of the room, playing cards or watching TV. Reporters rarely approach Bonds, knowing he is unlikely to talk to them.

When Bonds does talk, however, it is refreshing. Many of today’s players have been raised on SportsCenter sound bites, and answer in cliches. Bonds just fires away. If Derek Jeter’s answers are as bland as dry toast, Bonds’ are as spicy as a plate of hot peppers. Sometimes they are hard to swallow, but they are never dull.

“If you don’t freaking do your job, it doesn’t matter anyway,” Bonds said. “You could come in here and kiss everybody’s ass and tell everybody you love them and all this other crap, but if you ain’t performing on that field, you ain’t going to be here anyway.

“Me, I chose to play the game. What you see is what you get.”

This spring his image has taken another hit with the steroids investigation of Bay Area Laboratories Co-Operative near San Francisco. Bonds’ trainer, Greg Anderson, and his nutritionist Victor Conte Jr., are among four men indicted on charges of illegally supplying performance-enhancing drugs from BALCO. This has just added to the speculation that Bonds used steroids, which began in his record-breaking 2001 season. Fans seem split on whether they care if Bonds did use steroids, but if it is proven he used them, it will certainly influence how he is viewed by history. If it is not proven, the allegations may still hang over his head.

“He can never prove he didn’t do steroids,” Tygiel said. “Even if they test him now, and he shows no traces, there will still be people who think he used them and that it invalidates his legacy.”

Bonds will stand in Cooperstown one day soon. He turns 40 in July and said he thinks he’ll play only a few more seasons. When he does, will we be celebrating the player or still trying to figure out the man?

It is human nature to forget the bad and remember the good, and players like Ted Williams, Joe DiMaggio and Pete Rose had frosty relationships with fans and media during their careers, only to be embraced late in their lives. Some baseball historians feel Bonds will become beloved as he gets older. Others think there will always be a split decision when it comes to the slugger. Yankees outfielder Gary Sheffield, a close friend of Bonds, thinks it may take even longer for people to recognize what Bonds did.

“He’s never going to get the respect that he’s the best player of all-time until he’s dead,” Sheffield said.

When the question of how he’ll be viewed by history is posed to Bonds, he pauses. He looks the questioner in the eyes, flashes a Cheshire Cat smile and simply says, “I think I’ll be remembered.”

Barry in Bronx not likely

Giants slugger Barry Bonds told The Post in an exclusive interview that he likely will play only two more seasons. He already feels as if he no longer can play every day due to a balky back. Bonds said it would be different if he were on an American League team and could be just a designated hitter. Could that mean we may see Bonds in pinstripes before his career is done? Don’t count on it.

“If George [Steinbrenner] wanted me, George would have had me a long time ago,” Bonds said. “George don’t want me on that team because I might stir up too much [stuff] over there, which I might, but who cares?”